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Author Topic: Weird harmonic issue  (Read 914 times)

c0t0d0s0

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Weird harmonic issue
« on: February 16, 2013, 07:32:19 AM »

I've got a 2011 DS that I bought with 86 miles on the clock.  One thing that I've noticed is that when I accelerate I start hearing a sound almost like a person running a wet finger around the rim of a wine glass.  It changes pitch a little until 30mph when it goes away.

Is this normal?
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Doctorbass

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Re: Weird harmonic issue
« Reply #1 on: February 16, 2013, 08:47:47 AM »

Curious.. can you record it and show it to us?

Is it proportional to the motor and wheel speed?

Is it a pitch with no harmonics ( just the fundamental) like a wistle? or is it a complex sound... ? more sinewave? more square wave?

does it happen with the rear wheel off the ground? ( no load) ?

Please try having more details and also try finding whwre exactly it come from? motor? belt ? pulley ? wheel?

maybe it's just the brake friction that make that sound on the disk brake and that it just need to be readjusted?

Doc
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nigezero

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Re: Weird harmonic issue
« Reply #2 on: February 16, 2013, 10:37:36 AM »

You know what? I noticed a very distinct change in motor sound just before my brushes burned out . Logically, as the load on each brush changed, presumably as some were starting to jam up and not make contact properly this might explain it.

The noise changed from a normal motor whine to a higher pitched more hard drive sort of noise- hard to describe but notably different from the first 1000kms. I assumed it might be a bedding in thing but turned out to be a warning of impending problems
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manlytom

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Re: Weird harmonic issue
« Reply #3 on: February 16, 2013, 06:10:49 PM »

Hi. Is ur DS belt or chain drive? On my 2011S I had a slight whistle not from. Motor but belt. Use some belt lube and it went away.

Its great what we can hear when no ICE is in the way.  :)
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Tom
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CliC

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Re: Weird harmonic issue
« Reply #4 on: February 22, 2013, 11:54:46 AM »

My 2012 DS has one or two resonant metal bits that make that noise at low speeds, albeit accompanied by a little buzzing. Still haven't tracked them down, but I've hardly ridden at all lately.
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Bikes: 2012 Zero DS ZF9, 2000 Harley Road King (sold), 1985 Suzuki GN400 (sold)
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